The Federal Government has slammed Optus for its handling of a major cyber-attack. 

Almost a fortnight since Optus revealed it had been the victim of a cyber attack in which the names, birthdates, phone numbers, healthcare and passport details of up to 9.8 million Australians were potentially compromised.

Government Services Minister Bill Shorten says Services Australia wrote to Optus on September 27, requesting details of all affected customers whose Medicare and Centrelink details were leaked.

He says Optus still has not handed over the data to the government.

“The drawbridge needs to come down,” Mr Shorten said.

“We know that Optus is trying to do what they can, but having said that, it's not enough.

“It's been 11 days since the breach - it is peculiar that we still can't identify who for example used their Medicare information - their number - to be able to get identification.”

Services Australia intends to use the information to place additional security measures on the records of affected customers.

“We need this not tomorrow or the next day, we really needed it days ago,” Mr Shorten said on Sunday.

“We want to protect Australians' information that's held by government, we want to prevent further fraud and we seek Optus to step up its communication and transparency with government.”

Optus has been criticised for only contacting the 10,200 people whose data has already been leaked online by email.

“It is crucial everyone who has been affected by this breach is properly notified of that,” Cyber Security Minister Clare O'Neil says.

“An email is simply not sufficient under these circumstances.”

Optus has issued statements saying it is working “very closely” with federal, state and territory agencies to “determine which customers are required to take any action”.

“We continue to seek further advice on the status of customers whose details have since expired,” Optus said.

“Once we receive that information, we can notify those customers.

“We continue to work constructively with governments and their various authorities to reduce the impact on our customers.”

The issues has also cast doubt on Optus’ multi-billion-dollar military business.